Co-Investigators, in cooperation with NIDDK staff, recently created a four-center surgical research consortium, the Teen-Longitudinal Assessment of Bariatric Surgery or Teen-LABS (U01 DK072493). Designed as a prospective, longitudinal bariatric cohort observational study, the initial aims of Teen-LABS are to mirror key data collection elements of the adult surgical research consortium (Longitudinal Assessment of Bariatric Surgery) (LABS) to document the safety of bariatric surgery in adolescence and the post-operative health outcomes at 6, 12- and 24-months as compared to adult outcomes. Adolescent bariatric surgery occurs at an important time in psychosocial development-a period of rapid change in emotional, interpersonal, social, and career/vocational domains in which good adaptation bodes well for continued positive adaptation in the transition to emerging adulthood (ages 18-20). Bariatric surgery has the potential to positively alter the psychosocial and resultant developmental trajectory of adolescents with extreme obesity. As currently designed, Teen-LABS does not consider the adolescent patient within age-salient psychosocial and developmental paradigms and lacks an adolescent non-operative comparative group-critical gaps important to elucidating the risks and benefits of surgery during this unique developmental stage. To address these gaps, this ancillary study to Teen-LABS will utilize a prospective, controlled, longitudinal design and follow two parallel cohorts of adolescents over the same course of time: 170 Teen-LABS participants (ages 14-18) and 236 demographically matched non-operative extremely obese adolescents recruited from two Teen-LABS sites. Both cohorts will complete a series of measures at baseline/pre-surgery and at various time-points within the first 2 years post surgery. In addition to data elements already assessed within the Teen-LABS protocol (BMI, depressive symptoms, binge eating, quality of life), the present study will document the positive impact of surgery on additional domains of age-salient adolescent psychosocial functioning (e.g., perceived competence, peer victimization, social support, body image) and factors that may account for individual variations in psychosocial functioning (impaired parent/family functioning, health risk behaviors, high risk contexts). In addition, the ancillary study will add a critically important 24-month outcome measure to Teen-LABS-the attainment of age-salient developmental tasks of emerging adulthood (ages 18-20) (i.e., academic attainment, work competence, social/romantic involvement). The addition of a demographically matched non-operative extremely obese comparison group will provide vital information regarding the natural course of adolescent extreme obesity-a context in which to evaluate the relative impact of bariatric surgery on the long-term psychosocial and developmental well being of extremely obese adolescents. Hence, the innovative aims and research design of the proposed study will significantly enhance the scientific contribution of the Teen-LABS.